An A380 has about 1,400 kN available from its four engines. A twin engine A380 would need two engines developing at least 650-700 kN just to get off the ground.

An A380 has about 1,400 kN available from its four engines. A twin engine A380 would need two engines developing at least 650-700 kN just to get off the ground. For reference, the GE9X being developed for the 777X develops 470 kN. To make things more complex, there are regulations that require an aircraft to be able to continue takeoff should one engine fail. To match the thrust available of an A380 on 3 engines would require nearly 1000 kN of thrust from a single engine, way beyond current commercial jet engine technology.